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Flood in Mason County, Illinois
28 floods and flash floods events in the NCEI Storm Events record, 1950 to 2026. Event types counted: Flood, Flash Flood, Coastal Flood, Lakeshore Flood.
NCEI notes that Storm Data is compiled from a variety of sources including the National Weather Service, other federal, state and local agencies, the media and the public; that property and crop damage figures are estimates; and that some events are recorded by NWS forecast zone rather than by county. FEMA notes that NFIP claim records are redacted and aggregated to protect the privacy of policyholders. Storm records through 30 Jun 2026.
NCEI records 28 flood events in Mason County, Illinois, between 1950 and 2026, spread over 14 years.
June is the busiest month, with 8 of the recorded events. The last 20 years account for 16 events against 12 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 0.4% of the 6,507 flood events recorded in Illinois; its 5.2 per 100 square miles compares with 11.7 statewide.
NCEI attributes 1 death in the county to floods and flash floods.
Compared with Illinois
| Measure | Mason County | Illinois | US |
|---|---|---|---|
| Flood events since 1950 | 28 | 6,507 | 183,559 |
| Per 100 square miles | 5.2 | 11.7 | 5.2 |
| Per 10,000 residents | 21.7 | 5.1 | 5.5 |
| Deaths recorded | 1 | 61 | 2,961 |
| Busiest month | June | June | June |
By year
Seasonality
1Feb
4Mar
1Apr
4May
3Jun
8Jul
4Aug
2Sep
1Oct
0Nov
0Dec
0
Recorded events
All 28 events, most recent first. Magnitude is hail size, tornado rating or wind speed as recorded.
| Date | Event type | Magnitude | Property damage | Crop damage | Deaths | Injuries | Geography |
|---|---|---|---|---|---|---|---|
| 22 Feb 2023 | Flash Flood | — | — | — | — | — | County |
| 9 Jul 2020 | Flash Flood | — | — | — | — | — | County |
| 29 Apr 2017 | Flash Flood | — | — | — | — | — | County |
| 29 Apr 2017 | Flood | — | — | — | — | — | County |
| 12 Aug 2016 | Flash Flood | — | — | — | — | — | County |
| 28 Jun 2015 | Flash Flood | — | — | — | — | — | County |
| 26 Jun 2015 | Flash Flood | — | — | — | — | — | County |
| 26 Jun 2015 | Flash Flood | — | — | — | — | — | County |
| 7 Jun 2015 | Flash Flood | — | — | — | — | — | County |
| 1 May 2013 | Flood | — | — | — | — | — | County |
| 18 Apr 2013 | Flood | — | $5.0M | — | — | — | County |
| 15 Jun 2011 | Flash Flood | — | — | — | — | — | County |
| 15 Apr 2011 | Flash Flood | — | — | — | — | — | County |
| 28 Jul 2010 | Flash Flood | — | — | — | — | — | County |
| 19 Jul 2010 | Flash Flood | — | — | — | — | — | County |
| 22 Jun 2010 | Flash Flood | — | — | — | — | — | County |
| 11 Sep 2006 | Flash Flood | — | — | — | — | — | County |
| 25 Aug 2004 | Flash Flood | — | — | — | — | — | County |
| 9 Jul 2003 | Flash Flood | — | — | — | — | — | County |
| 13 Jun 2002 | Flash Flood | — | — | — | — | — | County |
| 1 Jun 2002 | Flood | — | — | — | — | — | Forecast zone |
| 12 May 2002 | Flood | — | — | — | 1 | — | Forecast zone |
| 11 May 2002 | Flash Flood | — | — | — | — | — | County |
| 27 Feb 1998 | Flood | — | — | — | — | — | Forecast zone |
| 15 Feb 1998 | Flood | — | — | — | — | — | Forecast zone |
| 10 Jan 1998 | Flood | — | — | — | — | — | Forecast zone |
| 1 Mar 1997 | Flood | — | — | — | — | — | Forecast zone |
| 21 Feb 1997 | Flood | — | — | — | — | — | Forecast zone |
Questions and answers
How many flood events has Mason County had?
28 events in the NCEI Storm Events record between 1950 and 2026. Reporting of floods and flash floods became far more complete after 1996, so early decades undercount.
When was the last recorded flood event in Mason County?
22 Feb 2023 (Flash Flood). Records reach NCEI about 120 days after the month ends.
What was the most damaging flood event recorded in Mason County?
The flood of 18 Apr 2013, with property damage estimated by NCEI at $5.0M.
How does Mason County compare with Illinois for flood?
5.2 events per 100 square miles against 11.7 statewide; the county holds 28 of the state's 6,507 recorded events.
Provenance
NOAA NCEI Storm Events Database, yearly details files through 30 Jun 2026, public domain. County-recorded events plus zone-recorded events whose forecast zone is named for the county (marked "Forecast zone"). Population and area from the US Census Bureau (2021). Built 1 Oct 2026. See the methodology, the Flood hub and the county page.